django-rest-framework/rest_framework/compat.py

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"""
The :mod:`compat` module provides support for backwards compatibility with older versions of django/python.
"""
import django
# cStringIO only if it's available, otherwise StringIO
try:
import cStringIO as StringIO
except ImportError:
import StringIO
def get_concrete_model(model_cls):
try:
return model_cls._meta.concrete_model
except AttributeError:
# 1.3 does not include concrete model
return model_cls
# First implementation of Django class-based views did not include head method
# in base View class - https://code.djangoproject.com/ticket/15668
if django.VERSION >= (1, 4):
from django.views.generic import View
else:
from django.views.generic import View as _View
from django.utils.decorators import classonlymethod
from django.utils.functional import update_wrapper
class View(_View):
@classonlymethod
def as_view(cls, **initkwargs):
"""
Main entry point for a request-response process.
"""
# sanitize keyword arguments
for key in initkwargs:
if key in cls.http_method_names:
raise TypeError(u"You tried to pass in the %s method name as a "
u"keyword argument to %s(). Don't do that."
% (key, cls.__name__))
if not hasattr(cls, key):
raise TypeError(u"%s() received an invalid keyword %r" % (
cls.__name__, key))
def view(request, *args, **kwargs):
self = cls(**initkwargs)
if hasattr(self, 'get') and not hasattr(self, 'head'):
self.head = self.get
return self.dispatch(request, *args, **kwargs)
# take name and docstring from class
update_wrapper(view, cls, updated=())
# and possible attributes set by decorators
# like csrf_exempt from dispatch
update_wrapper(view, cls.dispatch, assigned=())
return view
# PUT, DELETE do not require CSRF until 1.4. They should. Make it better.
if django.VERSION >= (1, 4):
from django.middleware.csrf import CsrfViewMiddleware
else:
import hashlib
import re
import random
import logging
import urlparse
from django.conf import settings
from django.core.urlresolvers import get_callable
try:
from logging import NullHandler
except ImportError:
class NullHandler(logging.Handler):
def emit(self, record):
pass
logger = logging.getLogger('django.request')
if not logger.handlers:
logger.addHandler(NullHandler())
def same_origin(url1, url2):
"""
Checks if two URLs are 'same-origin'
"""
p1, p2 = urlparse.urlparse(url1), urlparse.urlparse(url2)
return p1[0:2] == p2[0:2]
def constant_time_compare(val1, val2):
"""
Returns True if the two strings are equal, False otherwise.
The time taken is independent of the number of characters that match.
"""
if len(val1) != len(val2):
return False
result = 0
for x, y in zip(val1, val2):
result |= ord(x) ^ ord(y)
return result == 0
# Use the system (hardware-based) random number generator if it exists.
if hasattr(random, 'SystemRandom'):
randrange = random.SystemRandom().randrange
else:
randrange = random.randrange
_MAX_CSRF_KEY = 18446744073709551616L # 2 << 63
REASON_NO_REFERER = "Referer checking failed - no Referer."
REASON_BAD_REFERER = "Referer checking failed - %s does not match %s."
REASON_NO_CSRF_COOKIE = "CSRF cookie not set."
REASON_BAD_TOKEN = "CSRF token missing or incorrect."
def _get_failure_view():
"""
Returns the view to be used for CSRF rejections
"""
return get_callable(settings.CSRF_FAILURE_VIEW)
def _get_new_csrf_key():
return hashlib.md5("%s%s" % (randrange(0, _MAX_CSRF_KEY), settings.SECRET_KEY)).hexdigest()
def get_token(request):
"""
Returns the the CSRF token required for a POST form. The token is an
alphanumeric value.
A side effect of calling this function is to make the the csrf_protect
decorator and the CsrfViewMiddleware add a CSRF cookie and a 'Vary: Cookie'
header to the outgoing response. For this reason, you may need to use this
function lazily, as is done by the csrf context processor.
"""
request.META["CSRF_COOKIE_USED"] = True
return request.META.get("CSRF_COOKIE", None)
def _sanitize_token(token):
# Allow only alphanum, and ensure we return a 'str' for the sake of the post
# processing middleware.
token = re.sub('[^a-zA-Z0-9]', '', str(token.decode('ascii', 'ignore')))
if token == "":
# In case the cookie has been truncated to nothing at some point.
return _get_new_csrf_key()
else:
return token
class CsrfViewMiddleware(object):
"""
Middleware that requires a present and correct csrfmiddlewaretoken
for POST requests that have a CSRF cookie, and sets an outgoing
CSRF cookie.
This middleware should be used in conjunction with the csrf_token template
tag.
"""
# The _accept and _reject methods currently only exist for the sake of the
# requires_csrf_token decorator.
def _accept(self, request):
# Avoid checking the request twice by adding a custom attribute to
# request. This will be relevant when both decorator and middleware
# are used.
request.csrf_processing_done = True
return None
def _reject(self, request, reason):
return _get_failure_view()(request, reason=reason)
def process_view(self, request, callback, callback_args, callback_kwargs):
if getattr(request, 'csrf_processing_done', False):
return None
try:
csrf_token = _sanitize_token(request.COOKIES[settings.CSRF_COOKIE_NAME])
# Use same token next time
request.META['CSRF_COOKIE'] = csrf_token
except KeyError:
csrf_token = None
# Generate token and store it in the request, so it's available to the view.
request.META["CSRF_COOKIE"] = _get_new_csrf_key()
# Wait until request.META["CSRF_COOKIE"] has been manipulated before
# bailing out, so that get_token still works
if getattr(callback, 'csrf_exempt', False):
return None
# Assume that anything not defined as 'safe' by RC2616 needs protection.
if request.method not in ('GET', 'HEAD', 'OPTIONS', 'TRACE'):
if getattr(request, '_dont_enforce_csrf_checks', False):
# Mechanism to turn off CSRF checks for test suite. It comes after
# the creation of CSRF cookies, so that everything else continues to
# work exactly the same (e.g. cookies are sent etc), but before the
# any branches that call reject()
return self._accept(request)
if request.is_secure():
# Suppose user visits http://example.com/
# An active network attacker,(man-in-the-middle, MITM) sends a
# POST form which targets https://example.com/detonate-bomb/ and
# submits it via javascript.
#
# The attacker will need to provide a CSRF cookie and token, but
# that is no problem for a MITM and the session independent
# nonce we are using. So the MITM can circumvent the CSRF
# protection. This is true for any HTTP connection, but anyone
# using HTTPS expects better! For this reason, for
# https://example.com/ we need additional protection that treats
# http://example.com/ as completely untrusted. Under HTTPS,
# Barth et al. found that the Referer header is missing for
# same-domain requests in only about 0.2% of cases or less, so
# we can use strict Referer checking.
referer = request.META.get('HTTP_REFERER')
if referer is None:
logger.warning('Forbidden (%s): %s' % (REASON_NO_REFERER, request.path),
extra={
'status_code': 403,
'request': request,
}
)
return self._reject(request, REASON_NO_REFERER)
# Note that request.get_host() includes the port
good_referer = 'https://%s/' % request.get_host()
if not same_origin(referer, good_referer):
reason = REASON_BAD_REFERER % (referer, good_referer)
logger.warning('Forbidden (%s): %s' % (reason, request.path),
extra={
'status_code': 403,
'request': request,
}
)
return self._reject(request, reason)
if csrf_token is None:
# No CSRF cookie. For POST requests, we insist on a CSRF cookie,
# and in this way we can avoid all CSRF attacks, including login
# CSRF.
logger.warning('Forbidden (%s): %s' % (REASON_NO_CSRF_COOKIE, request.path),
extra={
'status_code': 403,
'request': request,
}
)
return self._reject(request, REASON_NO_CSRF_COOKIE)
# check non-cookie token for match
request_csrf_token = ""
if request.method == "POST":
request_csrf_token = request.POST.get('csrfmiddlewaretoken', '')
if request_csrf_token == "":
# Fall back to X-CSRFToken, to make things easier for AJAX,
# and possible for PUT/DELETE
request_csrf_token = request.META.get('HTTP_X_CSRFTOKEN', '')
if not constant_time_compare(request_csrf_token, csrf_token):
logger.warning('Forbidden (%s): %s' % (REASON_BAD_TOKEN, request.path),
extra={
'status_code': 403,
'request': request,
}
)
return self._reject(request, REASON_BAD_TOKEN)
return self._accept(request)
# timezone support is new in Django 1.4
try:
from django.utils import timezone
except ImportError:
timezone = None
# dateparse is ALSO new in Django 1.4
try:
from django.utils.dateparse import parse_date, parse_datetime
except ImportError:
import datetime
import re
date_re = re.compile(
r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$'
)
datetime_re = re.compile(
r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
r'[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
r'(?P<tzinfo>Z|[+-]\d{1,2}:\d{1,2})?$'
)
time_re = re.compile(
r'(?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
)
def parse_date(value):
match = date_re.match(value)
if match:
kw = dict((k, int(v)) for k, v in match.groupdict().iteritems())
return datetime.date(**kw)
def parse_time(value):
match = time_re.match(value)
if match:
kw = match.groupdict()
if kw['microsecond']:
kw['microsecond'] = kw['microsecond'].ljust(6, '0')
kw = dict((k, int(v)) for k, v in kw.iteritems() if v is not None)
return datetime.time(**kw)
def parse_datetime(value):
"""Parse datetime, but w/o the timezone awareness in 1.4"""
match = datetime_re.match(value)
if match:
kw = match.groupdict()
if kw['microsecond']:
kw['microsecond'] = kw['microsecond'].ljust(6, '0')
kw = dict((k, int(v)) for k, v in kw.iteritems() if v is not None)
return datetime.datetime(**kw)
# Markdown is optional
try:
import markdown
def apply_markdown(text):
"""
Simple wrapper around :func:`markdown.markdown` to set the base level
of '#' style headers to <h2>.
"""
extensions = ['headerid(level=2)']
safe_mode = False,
md = markdown.Markdown(extensions=extensions, safe_mode=safe_mode)
return md.convert(text)
except ImportError:
apply_markdown = None
# Yaml is optional
try:
import yaml
except ImportError:
yaml = None
import unittest
try:
import unittest.skip
except ImportError: # python < 2.7
from unittest import TestCase
import functools
def skip(reason):
# Pasted from py27/lib/unittest/case.py
"""
Unconditionally skip a test.
"""
def decorator(test_item):
if not (isinstance(test_item, type) and issubclass(test_item, TestCase)):
@functools.wraps(test_item)
def skip_wrapper(*args, **kwargs):
pass
test_item = skip_wrapper
test_item.__unittest_skip__ = True
test_item.__unittest_skip_why__ = reason
return test_item
return decorator
unittest.skip = skip
# xml.etree.parse only throws ParseError for python >= 2.7
try:
from xml.etree import ParseError as ETParseError
except ImportError: # python < 2.7
ETParseError = None